Weighing the Value of Bioenergy — Accounting for Land Carbon and the Timing of Emissions

Licentiate thesis, 2026

EU accounting and most energy-system models treat bioenergy as carbon neutral at the point of combustion, yet harvesting biomass reduces the carbon held in the land. This thesis asks, across three linked studies, what bioenergy is worth to a carbon-neutral European energy system once those land carbon stock changes are counted. Paper III derives a welfare-consistent rate for weighting CO2 emitted in different years, in place of the discount rates and time horizons that carbon accounting fixes by convention. Expert-elicited normative parameters and probabilistic climate–economy pathways give a median rate of 0.6% per year (0.31% under expected-welfare aggregation), far below the social discount rate because rising marginal damages offset most of the discounting. The variation is driven mainly by normative choices rather than empirical uncertainty about growth or warming. Paper II applies the CO2 weighting rate within ClimFor, a mass-balanced model tracking carbon from forest growth through harvest, processing, use, and disposal, across some 40 EU wood products. Against a no-harvest counterfactual, the EU forestry and wood sector is a net climate cost of roughly 165 Mt CO2 eq per year – not the sink assumed in policy and life-cycle assessment – and stays a net source under every baseline, weighting and substitution treatment tested. Paper I supplies the resulting emission factors to the energy-system model PyPSA- Eur. Internalizing them cuts cost-optimal biomass use by 52%, driving stemwood and its residues from the mix as wind and solar expand in their place.